Carburetor



May 13, 1958 C. R. GOODYEAR CARBURETOR Filed Nov. 7, 1955 FIG.I.

INVENTOR. CH RLES R. 6000mm BY 2*! ATTORNEYS United States Patent CARBURETOR Charles R. Goodyear, Detroit, Mich., assignor to Holley Carburetor Company, Van Dyke, M1ch., a corporation of Michigan Application November 7, 1955, Serial No. 545,159

4 Claims. (Cl. 261--78) The present invention relates to a carburetor and more particularly, to a device for improving the character of the discharge from the main nozzle of the carburetor.

It is an object of the present invention to provide means for improving the character of discharge of liquid fuel in a carburetor from the main nozzle into the venturi.

More specifically, it is an object of the present invention to provide annular means located at the upstream side of the discharge port of the main nozzle including an annular surface directly above the discharge port and preferably at least partially overhanging the port.

Still more specifically, it is an object of the present invention .to provide a construction as described in the preceding paragraph in which the surface is conically inclined and intersects the inner surface of the throat of the venturi to provide an acute included angle intersection therewith.

Other objects and features of the invention will become apparent as the description proceeds, especially when taken in conjunction with the accompanying drawings, wherein:

Figure 1 is a schematic sectional view showing the improved carburetor.

Figure 2 is an enlarged sectional view showing the discharge port and overhanging lip of the venturi.

Referring now to the drawings the carburetor is illustrated as of the downdraft type and includes a bowl 10 containing liquid fuel the level of which is maintained in the bowl as indicated at 12 by suitable means such as a flow controlled inlet valve. The carburetor includes an air induction passage and mixing chamber indicated generally at 14 which is provided with a venturi 16 having a throat as indicated at 18. A booster venturi indicated generally at 20 is provided having its discharge end located in the throat of the main venturi.

The main fuel supply comprises a main metering jet 22 through which liquid fuel is drawn into the well 24. When the engine to which the carburetor is attached is not running, it will be understood that fuel flows by gravity into the well to a level corresponding to the level of the fuel in the bowl. When the engine is running air drawn through the induction passage operates to reduce pressure at the throats of the two venturis and accordingly, fuel is drawn upwardly through the tube 25 through the passage 26 where it is discharged from a port 28 opening into the booster venturi 20. This liquid fuel is atomized and mixed with the air being drawn throughthe booster venturi.

In the past the usual construction of the main nozzle located in the throat of the booster venturi was a tubular extension having an open end located generally within the throat of the venturi. Since the discharge port of this tubular nozzle was ordinarily of small size, it had the effect of concentrating the discharge of fuel into the air stream passing the booster venturi and substantially through the main venturi. This concentration of the discharge of fuel tended to operate against effective atomization and caused poor distribution of the fuel in the 2,834,587. Patented May 1 3, v1958 mixture. As seen in the figures, the booster venturi 20 is provided with an inserted member 30 shaped to provide a lip indicated generaly at 32. This lip includes a shoulder surface 34 which is an annular surface, preferably of conical shape, located directly above or at the upstream side of the port 28. Moreover, as will be observed in the figures the surface 34 intersects the smooth interior surface 36 at the throat of the booster venturi to provide a lip of acute included angle cross-section at least partially overlying or overhanging the port 28.

As a result of this construction substantial improvement in the discharge of fuel into the air stream is effected. As the fuel flows through the port 28 it is at least partially intercepted by the lip 32 which forms a downwardly facing step or shoulder in the booster venturi. In the space immediately beneath the step or shoulder surface 34 there will exist a low pressure area into which fuel emerging from the port 28 will be drawn. Fuel thus drawn into the annular space .below the lip will to a substantial extent flow around this annular surface and will be drawn from the sharp acute angled edge defined by the intersectionbetween the shoulder surface 34 and .the inner venturi surface 36 by the air flowing at high velocity therethrough. In accordance with this invention the fuel is thus introduced into the air stream from an annular edge having a diameter many times greater than that of the discharge port 28. Accordingly, the fuel will initially flow into the air stream in the venturi in a manner adapted to produce substantially improved mixture and atomization.

The modified construction provides in association with the inwardly directed discharge port 22, a convex conical surface 34 which at its opposite edges intersects the surface of the throat of the venturi at acute angles. Where the larger end of the conical surface intersects the surface of the venturi, there is provided a downwardly facing channel of V-shaped cross-section, and the acute angled intersection between the surface 34 and the surface of the venturi provides a structure around which liquid fuel will flow. At the same time, the intersection at the opposite edge of the conical surface 34 with the surface 36 produces the knife edge 32 best seen in Figure 2, from which the fuel is drawn efficiently in a fine spray occupying a circular zone extending at least partially around the throat of the venturi.

It will be appreciated that when the engine starts to run, fuel will be drawn into the main venturi in steps. In the first place, as the pressure differential between the bowl and the throat of the venturi is first initiated, fuel may flow downwardly over the interior surface of the venturi. This normally represents inefficient fuel-air mixture but occurs at a time when sufiicient proper fuelair mixture is being introduced into the manifold from the transfer port system indicated generally at 40. When the pressure differential increases slightly the fuel is partially picked up by the shoulder surface 34 and fiows around this surface to an extent dependent upon the pressure differential or the degree of vacuum built up in the booster venturi. Finally, under normal operation, sufficient fuel is drawn through the passage 36 and port 28 so that it flows completely around the surface 34 and sprays off the sharp acute angled edge thereof in the most efiicient manner.

The compound annular surface including the annular surface 34 and the upper portion of the inner surface of 3 the booster venturi 20 in the horizontal plane of the port 28 is, except for the opening of the port 28, a continuous reentrant surface.

The drawings and the foregoing specification constitute a description of the improved carburetor in such full, clear, concise and exact terms as to enable any person skilled inthe art to practice the invention, the scope of which is indicated by the appended claims.

What I claim as my invention is:

1. In a downdraft carburetor having an induction passage in which air and liquid fuel are mixed, said passage having a venturi portion provided with a restricted throat,

a fuel supply system including a passage having a port opening radially inwardly into a side of said venturi adjacent its throat, said venturi comprising an annular lip of acute included angle cross-section located upstream from and above said port and partially overhanging said port. 1

'2. In a downdraft carburetor having an induction passage in which air and liquid fuel are mixed, said passage having a venturi portion provided with a restricted throat, a fuel supply system including a passage having a port ing an inclined annular conical surface at least partially overlying said port, said surface intersecting the inner convex conical surface extending around the throat opening radially inwardly into a side of said venturi adjacent its throat, said venturi having an annular surface above and at the upstream side of said port partially overhanging said port and terminating radially inwardly of said venturi in a sharp acute'angled edge.

3. A downdraft carburetor comprising a venturi having an annular shoulder providing a surface facing downstream and having a sharp inner edge, a fuel supply port of limited angular extent located immediately adjacent said shoulder at its downstream side, said shoulder havthereof from a point directly above said port to a point intermediate the upper and lower edges of said port so as to partially overhang said port, said convex conical surface intersecting the surface of the throat of the venturi 1 at acute angles and defining therewith a downwardly opening channel of V-shaped cross-section, the" inner edge of said channel'tern'ainating in an acute angled edge portion effective to produce an eflicient spray of liquid fuel into the venturi from a circular zone at least partially surrounding the throat of the venturi. 1

References Cited in the tile of this patent UNITED STATES PATENTS 7 Great Britain Sept. 18, 

